Phosphogypsum (PG), as a by-product of the production of phosphoric acid, faces the problems of large annual output and difficult treatment. There is a large demand for fillers in the process of road paving, which may be an effective method for the utilization of PG resources. In this study, three proportions of phosphogypsum–lime–fly ash (PLF) mixture were designed, first, according to orthogonal tests. The comprehensive performance of the PLF mixture was tested by the compression rebound modulus test, unconfined compressive strength test, flexural tensile strength test, dry shrinkage test, and temperature shrinkage test, respectively. The results show that adding crushed stone to the PLF mixture can effectively improve the compression rebound modulus, unconfined compressive strength, and flexural tensile strength. The high content of PG in the mixture can also improve the dry shrinkage and temperature shrinkage properties of the mixture. According to the road layer requirements, the optimum proportion of the PLF mixture is recommended, which may benefit the road construction and PG resources.

To obtain the optimum workability of roller compacted concrete (RCC), it is necessary to fully consider the degree of influence of each component of RCC. In this research, the influence of water-cement ratio, the content of cement slurry, the content of mortar, the sand ratio, the particle size of maximum aggregate, and the content of mineral powder on the workability of RCC was studied by modified Vebe test. The results showed that the Vebe consistency decreased with the increase of water-cement ratio. The recommended range of cement slurry surplus parameter was 1.1∼1.4; the recommended range of cement mortar surplus parameter was 1.2∼1.6; mixing the fly ash and silica fume into RCC is beneficial to its workability, but the content of fly ash could not exceed 20 %, and the optimum value of the content of silica fume was between 5 and 7.5 %; and the sand ratio has a significant effect on RCC, and there is an optimal sand ratio just like ordinary concrete, which is 34 % in this study.

To address the problems of segregation, cracking, and poor flatness of the roller compacted concrete (RCC) used in the base of the construction, this research takes the Qinglian highway rehabilitation project as the research object. Based on the filling and wrapping method, the surplus parameters of cement slurry and the surplus parameters of mortar are introduced, and the method is used to design the mix ratio of RCC. The mixing ratios of the mixture were designed by the orthogonal test method. In this research, Vebe time, compactness, 28 days flexural strength, and compressive strength were used as the evaluation indicators for each mix ratio specimen. The test results show that the optimum Vebe consistency (VC) value is 33 s, which provides good compactivity; the degree of compaction is 98.5 %, which provides good workability; the appropriate amount of cement is 190 kg/m3, which not only meets the strength requirements but also reduces the occurrence of road distresses. This research combines the practical project with mixture ratio design and uses the indicators recommended in the design process to propose methods to reduce road quality problems and to provide a scientific basis for RCC construction control.